Hoist



Dec. 7, 1954 H. w. M. KING 2,696,365

2 Sheets-Sheet 1 Filed March 1, 1951 H. W. M. KING HOIST Dec. 7, 1954 Filed March 1, 1951 2 Sheets-Sheet 2 W, KW

in spaced parallel relationship. Mounted on United States Patent '0 f Henry Walter Mayer King,

Hitchin, England, a British Geo. W. King Lirr'iited, company Application March 1, 1951, Serial No. 213,415 6 Claims. (Cl. 254-173) The invention relates to power operated hoists of the kind wherein a load chain is led around a driving sprocket mounted in a pulley block, one end of said chain being anchored to the block or other convenient fixed point while the other is fitted with a grapple hook or like load engaging device.

In hoists of the kind indicated above it has been the practice to provide chain guards which comprise rockable arms or the like arranged to lie in proximity to those portions of the chain passing the driving sprocket, said arms being urged into their operative positions in proximity to the chain by resilient means and the arrangement being such that in the event of the chain becoming displaced from the sprocket or being kinked, twisted or otherwise deformed one or other of said chain guards,

depending upon the direction'of travel of the'chain, will be displaced automatically thereby to avoid damage to the chain and to the guard.

The invention is concerned with hoists of the kind referred to having chain guards of the type indicated above and it has for its chief object to provide means whereby-movement of the chainguards maybe employed lflor controlling the operation of the motor driving the oist.

According to the invention in a hoist of the kind referred to and having chain guards ofthe type above described means are provided whereby movement of one or other of the guards from its operative position is enivployed to cut ofi and if necessary to reverse the drive from the motor to the driving sprocket of the hoist.

In order that the said invention may be clearly understood and readily carried into effect the same will be hereinafter more fully described with reference to the accompanying drawings inwhich:

Fig. l is an end elevationalview of a hoist.

Fig. 2 is a plan view, partially in section, of the-hoist shown in Fig. 1.

Fig. 3 is a section on the line 3-3 of Fig. 2.-

Fig. 4is-a diagrammatic illustration of a suitable switch mechanism for controlling the reversible electric motor of a hoist embodying the present invention.

Fig. 5 is a wiring diagram showing theconnections between the power supply lines and motor through the switch mechanism of Fig. 4.

Referring now to the drawings it will be seen that the .hoist therein illustrated comprises a; main frame incorporating two side plates and 11 which are maintained the outer surface of the side plate 10 is a driving motor 12 having a controlling unit 13 associated therewith, said motor 12 being adapted to drive a shaft 14 which'passes through the usual chain sprocket 15 and serves to impart a drive to the latter through reduction gearing. The sprocket 15 is disposed between the plates 10 and 11 Mounted on the outer surface of the said plate 11 is a brake unit indicated generally by 16 which latter is adapted on operation to exert a braking effect on the rotor of the motor 12.

Disposed at opposite sides of the chain sprocket 15 are two pivoted chain guards 17 which are arranged to lie in proximity to those portions of the chain 18 passing around said sprocket. The guards 17 are interconnected at these upper ends by means of springs 19 which serve normally to retain said guards in the operative positions as shown in the drawings, the arrangement being such that in the event of thechain 18being displacedfrom the sprocket 17 or being kinked, twisted or otherwise de- 2,696,365 Patented Dec. 7, 1954 formed one or other of the guards, depending up'on the direction of travel of the chain, will be displaced outwardly away from -the sprocket against the action of the springs 19 thereby to avoid damage to the chain and to the guard. In most cases the chain 18 will be fitted with limit attachments at predetermined points, such attachments being designed to effect displacement of the appropriate guard when said chain has been raised or lowered to a preselected extent. Each of the chain guards 17 has a link pivotally connected thereto through the medium of a pin and slot connection. The links, which are designated by 20 and 21, are disposed in generally parallel relationship and at that endremote from'the guard each is pivotally connected to an arm, said arms, which are designated 22 and 23 respectively, being rigidly mounted on a common shaft 24 to' project radially therefrom. As will be seen from the drawings the two arms 22 and 23 are so mounted on the shaft 24 as to be in alignment. The shaft 24 constitutes the actuating shaft of the controlling unit 13' which latter serves to control the operation of the electric driving motor 12, said motor, as indicated above, being in turn adapted to drive the sprocket 15 of the hoist.

A suitable switch mechanism is shown in Fig. 4 to effect control of the reversible electric motor 12 in response to turning of shaft 24'. It will be seen that the switch mechanism of the control unit 13 may include fixed contacts L1 and M1, L2 and M2, and L3 and M3 which are respectively connected to the correspondingly identified lines L1, L2 and L3 of a three-phase supply system'and to the corresponding motor terminals M1, M2 and M3 of the reversible motor 12 (Fig. 5). Movable contacts A1, A2 and A3 are mounted on shaft 24 and insulated from the latter within the control unit 13' to cooperate with the contacts L1 and M1, L2 and M2, and L3 and M3 so that, when the'shaft 24 isin a neutral position, as shown on Fig. 4, all of the movable contacts are spaced from the respective fixed contacts, and the motor 12 is deenergized. However", when shaft 24 is turned from its neutral position in the direction of the arrow 2 (Fig. 4), movable contact A2 engages fixed contacts L2 and M2, while movable contact A1 engages fixed contacts L1 and M to complete the necessary circuit for rotation ofmotor 12 in one direction. If shaft 24 is turned from its neutral position 'in the direction of the arrow 3 (Fig. 4), movable contact A again engages fixed contacts L1 and M1, and contact A now engages fixed contacts L3 and M3, while contact A2is spaced from contactsL2 and M2, whereby the circuit for effecting reverse rotation of motor 12is closed. While a particular switch mechanism has been described above andillustrat'ed in the drawings, it is to be understood that any other suitable switch mechanism capable of effecting forward and reverse rotation of motor 12 in response to turning of shaft 24 may be employed in place thereof.

In operation according to whether it is desired to raise or lower the usual grapple hook or other load carrying device on the free end of the hoist chain 18 the actuating shaft 24 is turned about it's own axis in the appropriate direction to operate a switch inthe controlling unit 13 in such a manner as to cause operation of the motor 12 in the desired direction. In the embodiment illustrated actuation of the shaft 24 is effected by means of pull cords 25 which are attached to a' double armed lever 26 carried by said shaft. The rotational movement 'of the shaft 24 causes an axial displacement of the links 20 and 21 which is permitted without-any displacement of the chain guards 17 due to the pin and slot connections between said links and the guards i. e. each link will move longitudinally relatively to its conecting pin carried by the guards so as to bring such pin to one end of the slot in said link. As indicated above the direction of motion of the links 20 and 21 will depend on the direction of rotation of the shaft 24 i. e. on whether the hoist is to be raised or lowered. When raising or lowering of the chain 18 has proceeded to the desired extent a limit attachment associated with the chain will be brought into contact with the appropriate chain guard 17 and will cause the latter to pivot. The arrangement is such that pivotal movement of the chain guard 17 will cause a longitudinal movement to be imparted to the associated link 20 and 21 which will, due to its connection with the arm 22 or 23 carried by the shaft 24, impart a reverse angular movement to the latter to cause cutting off of the motor 12. It will be apparent that due to the fact that both links 20 and 21 are coupled to the control shaft both will have a longitudinal movement simultaneously but while the link coupled to the actuated guard will be positive in its action to rotate the shaft 24 angularly the second link will merely slide longitudinally due to the movement of the shaft there being no displacement of its associated chain guard. Such idling movement, which occurs in the case of one or other of the links 20 and 21, depending on the direction of travel of the chain and hence on which guard is actuated, is allowed for by virtue of the pin and slot connections between the links and their respective guards. The arrangement is further such that should for some reason or other the hoist chain continue to travel after the motor 12 has been switched off, thereby resulting in further displacement of the previously actuated chain guard, the latter will impart an additional movement to its associated link 20 or 21 causing the same, in turn, to impart a further angular movement to the shaft 24 such as will cause the switch in the controlling unit 13 to be operated to effect driving of the hoist motor 12 in the reverse direction.

The control exerted by the chain guards through the medium of links 20 and 21 and appendent mechanism is extended to include operation of the brake unit 16 which is adapted to retard the rotor of the motor 12. In the embodiment illustrated the lever 26 carries a pin 27 which is displaced with respect to the axis of rotation of the shaft 24 and is adapted to engage in a slot 28 formed in a link 29. The link 29 is in turn attached to a shaft 30 having a cam of equivalent device 31 associated therewith and adapted on angular movement of said link 29, due to angular movement of the shaft 24, to control the operation of a pair of brake shoes 32 arranged to cooperate with a brake drum 33 associated with the shaft 14 which latter is connected directly to the motor. It is to be noted that the brake unit 16 is not capable of sustaining a load present on the hoist chain 18 and for that purpose it will be necessary to incorporate a screw type friction brake or any other suitable type of brake which will be capable of sustaining such load.

The invention is not limited in its application to electrically driven hoists since it may for example be applied to hoists wherein the driving sprocket is driven from for example a petrol or other engine through the medium of a reversible gear. In such a case the angular movement of the shaft 24 one or other of the links 20 or 21 may be employed to control the operation of clutches and thereby to cut off or reverse the drive to the sprocket.

It will be appreciated that, although reference has been made to the actuation or displacement of the chain guards by limit attachments on the chain, displacement of said guards will also be effected should the chain be displaced from the sprocket wheel or become kinked, knotted twisted or otherwise deformed.

I claim:

1. In an electrically operated hoist wherein a load chain is led around a driving sprocket to which a drive is imparted by an electric motor and movable chain guards are disposed in proximity to those portions of the chain passing around said sprocket, the provision of means whereby displacement of one or other of the chain guards from its operative position will result in cutting off and reversal of the drive to the driving sprocket, such means comprising a switch mechanism adapted to control the motor, a shaft associated with said switch mechanism and adapted on rotational or angular movement to effect operation of the latter, linkage mechanisms connecting said shaft to each of the chain guards and lost motion means incorporated in said linkage mechanisms, the arrangement being such that on angular movement of the shaft to effect operation of the switch and to start the motor, the linkage mechanisms will be set so that on displacement of one or other of the chain guards a reverse angular movement will be imparted to the shaft, thereby to cut off and to reverse the motor.

2. In an electrically operated hoist wherein a load chain is led around a sprocket to which a drive is imparted by an electric motor and movable chain guards are disposed in proximity to those portions of the chain passing around said sprocket the provision of means whereby resultant on positive movement of displacement of one or other of the guards from its operative position will result in cutting off and reversal of the drive to the driving sprocket, such means compris ing two links, each of which is connected to a separate one of the chain guards by means of a pin and slot connection, a rotatable shaft to which said links are operatively connected and a control mechanism associated with said shaft and adapted to be actuated on rotational movement thereof to control the operation of the electric motor, the arrangement being such that on angular movement of the shaft to effect operation of the motor, the links will move relatively to the chain guards by virtue of the pin and slot connections and will be set so that on displacement of one or other of said guards a reverse angular movement will be imparted to said shaft thereby to cut off and to reverse said motor.

3. In an electrically operated hoist wherein a load chain is led around a drive sprocket to which a drive is imparted by an electric motor and movable chain guards are disposed in proximity to those portions of the chain passing around said sprocket, the provision of means whereby displacement of one or other of the chain guards from its operative position will result in cutting off and reversal of the drive to the driving sprocket, such means comprising two links which are disposed in spaced parallel relationship and each of which is connected to a separate one of the chain guards by means of a pin and slot con nection, a rotatable shaft, two arms fixedly mounted on said shaft to each of which one of said links is pivotally connected and a switch mechanism associated with said shaft and adapted to be actuated on rotational movement of the latter to control the operation of the electric motor, the arrangement being such that on angular movement of the shaft to effect operation of the motor, the links will move relatively to the chain guards by virtue of the pin and slot connections and will be set so that on displacement of one or other of said guards a reverse angular movement will be imparted to said shafts, thereby to cut off and to reverse said motor.

4. In an electrically operated hoist wherein a load chain is led around a drive sprocket to which a drive is imparted by an electric motor and movable chain guards are disposed in proximity to those portions of the chain passing around said sprocket, the provision of means whereby displacement of one or other of said chain guards from its operative position will result in cutting off of the drive to the drive sprocket, such means comprising a switch mechanism adapted to control the motor, a shaft associated with said switch mechanism and adapted on angular movement to effect operation of the latter, linkage mechanisms connecting said shaft to each of the chain guards, lost motion means incorporated in said linkage mechanisms, a brake mechanism associated with said motor, and means coupled to said shaft and brake mechanism and adapted on angular movement of the former to control the operation of the latter, the arrangement being such that on angular movement of the shaft to effect operation of the motor, the linkage mechanisms will be set so that on displacement of one or other of said guards a reverse angular movement will be imparted to said shaft thereby to effect operation of the switch mechanism and of the brake mechanism and to cause stoppage of the motor.

5. In an electrically operated hoist wherein a load chain is led around a drive sprocket to which a drive is imparted by an electric motor and movable chain guards are disposed in proximity to those portions of the chain passing around said sprocket, the provision of means whereby displacement of one or other of said chain guards from its operative position will result in cutting off of the drive to the drive sprocket, such means comprising two links, each of which is connected to a separate one of the chain guards by means of a pin and slot connection, a rotatable shaft towhich said links are operatively connected, a switch mechanism associated with said shaft and adapted to be actuated on rotational movement of the latter to control the operation of the electric motor, a brake mechanism comprising a brake drum associated with the motor shaft and co-operating brake shoes, cam means adapted to control the operation of the brake shoes, and linkage mechanism coupling said cam means to said shaft, the arrangement being such that on angular movement of the shaft to effect operation of the motor, the links will be moved relatively to the chain guards by virtue of the pin and slot connections and will be set so that on displacement of one or other of the chain guards a reverse angular movement will be imparted to said shaft, thereby to effect operation of the switch mechanism and also to move the cam means, thereby to efiect application of the brake mechanism and stoppage of the motor.

6. Means for controlling the operation of a hoist motor as claimed in claim 5 wherein a double armed actuating lever is mounted on the shaft to efiect angular movement of the latter and hence to control the operation of the hoist motor, such lever being coupled by means of a pin and slot connection to the linkage mechanism associated with the cam means, so that on movement of the lever to control the operation of the hoist motor the cam means will be operated to actuate the brake mechanism.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Number 910,798 Duntley Jan. 26, 1909 1,945,712 Wadd Feb. 6, 1934 10 2,274,175 Whitcomb Feb. 24, 1942 2,529,084 King Nov. 7, 1950 

